Researchers have identified genetic risk factors that may accelerate a teen's progression to becoming a lifelong heavy smoker. The team of scientists from the U.S., the U.K. and New Zealand examined earlier studies by other research teams to develop a genetic risk profile for heavy smoking. Then they looked at their own long-term study of 1,000 New Zealanders from birth to age 38 to identify whether individuals at high genetic risk got hooked on cigarettes more quickly as teens and whether, as adults, they had a harder time quitting.